SMART DOG MININGTM

It
takes a smart dog to find hidden treasures

SIEVE BENDS

Sieve bends are classification devices commonly used ahead of
vibrating screens for initial size separation and in dewatering
stages to remove the bulk of the water and very fine size particles
from the vibrating screen to reduce its load.They can be used by themselves in one or two-stage units
after cyclones or by themselves, and before flotation, again, as a
dewatering and classification step.The sieve bend is a curved, stationary sieve developed by the
Dutch State Mines organization.To im­prove screening efficiency, especially on very fine
coals, use of vibrating sieve bends has been done successfully at
several operations.

Equipment Sizing

The following tables are the general sizing characteristics for
sieve bends.As a
general rule the size of classification will be 3/4 to 1/2 of the
aperture depending on angle.Sharper and higher angle sieve bends will classify half the
sieve bend aperture, and flatter sieve bends will classify 3/4 sieve
bend aperture.

For dense medium sieve bends ahead
of drain and rinse screens use the following.

Equipment
Performance

Sieve bend feed is normally in the range of 25 to 35% solids
by weight, an average condition would be 30% solids.Classifying sieve bends, ahead of desliming screens and
handling coarser size material can be fed at higher solids
concentrations.
Des­liming sieve bends handling fine feed after cyclones can be fed
lower solids con­centration, commonly down to 5 to 10% solids by
weight.Sieve bend
handling +28 mesh feed will produce a product oversize of 35 to 50%
solids by weight.Sieve
bends handling finer sizes 28 mesh x 0 will produce 35% and lower
solids concentra­tions.
Misplaced materials in the sieve bends commonly runs on the order of
10% of the unders in the overs and 5% of the overs in the unders.